Boom shock absorber



R. A. EECKWITH BOOM SHOCK ABSORBER Filed OOC. 30, 1945 2 Sheets-Sheet l .IN1/mm3.

Sept 2, E947.,

56M 2 94? v R. A. BECKWITH 426,7

' BOOM SHOCK ABSORBER Filed oct. 30, 1945 2 Sheng-sheet 2 Patented Sept. 2, 1947 BooM snocx Ansonea Raymond A. Beckwith, Milwaukee, Wis., assignor to Koehring Company, Milwaukee, Wis., a corporation of Wisconsin Application October 30, 1945, Serial No. 625,556

14 Claims. 1

This invention pertains to the art of shovel excavating machines and involves the provision of an improved device located adjacent to the foot of the boom of a shovel excavator for absorbing torsional or lateral twisting strains produced on the boom by uneven digging pressures applied to the digging end of the dipper carried by the dipper stick customarily mounted on the boom, and other twisting strains that may be caused by the lateral sweeping of the boom as it carries the dipper stick and dipper with the contained load in the latter.

'Ihe shock absorber unit of myinvention is further so designed as to cushion the direct jar incident to rock shock loading and indeed cushion all bending strains incident to the operation of the dipper when it hits a particularly tough spot, so to speak, in the cut of the excavation, the cushion unit being generally designed to absorb all the stresses that would tend to injure the unprotected booms or dipper sticks.

A special further object of my invention has been to produce a construction of shock absorber unit of the class described which is relatively simple, exceedingly strong and rugged in its mounting on the boom, and its cooperation with the supporting shaft of the boom, and which is composed of relatively few parts readily accessible and which will efliciently perform the intended shock absorbing functions.

A full understanding of my invention and the merits of the construction proposed may be had upon reference to the following description in coniunction with the annexed drawings, in which:

Figure 1 is a side elevational view showing a crane or excavator traction body partly in dotted lines, and illustrating the boom and dipper stick features of the machine in full lines, the boom being shown equipped with the shock absorber means of my invention.

Figure 2 is a partial side elevation view of the lower portion of the boom, the foot of which is equipped with my shock absorbing device.

Figure 3 is a plan view of the portion of the boom shown in Figure 2, one of the side castings of the foot of the boom being illustrated in section, along with the bracket means which supports the pivot shaft connecting the boom to the body of the excavator.

Figure 4 is a vertical sectional view taken about on the line 4-4 of Figure 2 and bringing out somewhat more clearly the peculiar bearing connection between one of the cushion levers and the shaft bearing member mounted in the adjacent side of the foot of the boom.

t Now specifically describing my invention and referring to Figure 1, I note that the excavator body is partly illustrated at A in dotted lines, and the traction supporting means for said body Yof the machine is designated at B and similarly shown. In Figure 1, in full lines, there is illustrated the boom l which carries the usual dipper stick 2 having the dipper 3 at its working end. The boom I and the parts 2 and 3 may be largely conventional and may be operated in the customary way for the crowding out and racking in of the dipper.

The boom I, as seen best in Figures 2 and 3, may be generally described as bifurcated at its lower end in order to provide the boom foot portion l comprising the spaced side castings 5 which may be fabricated to join the body of the boom in any substantial manner, this feature not being particularly important to the invention so long as a rugged construction is provided. Each side member or casting 5 of the boom foot 4 is of the same construction as its associated member, so, in conjunction with Figure 2 one of these castings 5 and the shock absorbing devices associated therewith, will be set forth. The casting 5 is of course disposed generally longitudinally of the boom I and it is provided with a seat 6 in the form of an open recess that leads upwardly from the underside of the casting and receives therein the bearing box or block 1 which provides a suitable bearing for one end of the pivot shaft 8 which extends transversely of the foot 4 of the boom and provides a pivotal connection between the boom I and certain bracket means 9 and I0 which are carried upon the body A of the excavating machine. At its free end the casting 5 is formed with a somewhat hookshaped member II which is recessed on its inner side as shown at I2 to provide a receiving bearing portion for the lower end of a cushion lever I3. Each lever I3 is provided at its lower end with a short bearing arm I4 that is received in the seat I2 so as to interlock with the lower end of the casting 5 by engaging in such seat. A short distance from the bearing arm I4 of the lever I3 the latter is provided with a bearing block engaging portion designated I5 and seen best in Figures 2 and 4 of the drawing, which portion I5 snugly fits into and frictionally engages a recess in the lower end of the bearing block 'l which recess is contoured to conform with the rounded formation of the adjacent engaging portion I5 of the cushion lever I3.

From the end portion of the lever I3 which is equipped with the parts I4 and I5, the lever extends longitudinally of the casting or side member of the boom foot 4 for a considerable distance-indeed, practically to an extent corresponding approximately with the length of the casting 5, and at its outer or upper end said lever I3 is provided with an opening through which passes a spring supporting bolt I6. The bolt I6 likewise passes through an opening in the upper end of the casting 5 adjacent to the upper terminal of the lever I3, and a suitable coiled compression spring Il surrounds the bolt I6 and is held in place with one end resiliently bearing against the outer or upper end of the casting -5 and the other end similarly bearing against a spring backing plate I8 held in place on the bolt I6 by means of a. suitable nut I9. A nut or nuts 20 are also screwed on the lower end of the bolt I6, or the bolt may be headed at such end as desired.

Now it will be apparent from Figure 2\ that the upper side or inner side portion of the cushion lever I3 is relatively ilat and extends along the casting 5 adjacent to the lower ap portion of the latter.

With the parts as seen in Figure 2 it will be seen that if a torsional strain is received by the boom I such strain necessarily will be transmitted to the foot portion thereof, and if the resistance is incident to counter-clockwise movement of the boom longitudinal axis, when said resistance reaches a predetermined point, the casting 5, which would be the right hand casting shown in Figure 3, will rise and the lever I3 will rock on the arm portion It as a. fulcrum to afford a separating movement of the upper or outer portion of the lever I3 from the lower portion of the casting 5. This movement is permitted by the compression spring II which will be, of course, additionally compressed incident to such movement. Then when the said torsional strain is removed, the action of the spring I1 will be to pull the lever I3 to its normal or original position in relation to casting 5, as seen in Figure 2 that illustrates such position. When the casting 5 rises in relation to the axis shaft means 8, of course the bearing block I has a relative downward movement in the recess or seat 6 receiving the same incident to the pivoting movement of the lever I3 as above described.

The degree of movement of the levers I3 carried by the foot 4 of the boom of course varies de-v pendent lupon the amount of torsional or twisting stress produced on the boom around the longitudinal axis of the latter. In one direction of the creation of such stress, one lever I3 will absorb the cushion of the strain or jar or shock that may be incident to the production of the stress, and in the opposite direction, the other of the levers I3 will perform the same Work.

Under certain conditions, moreover, especially when the excavating dipper is working in rock or some tough spot in earth cut, there may be produced a very abnormal resistance to the direct crowding out or thrusting action of the dipper into the work or cut. When this happens, the two levers I3 at the foot 4 of the boom may yield simultaneously and thus aiford the absorbing of the direct shock produced at the side members at the foot 4; at this time of course the springs Il at the opposite sides of the boom will simultaneously absorb the strain produced, and in many instances prevent any breakage of the shaft at the pivot point of the boom or the brackets that supPOrt said shaft.

1f desired the springs I 'I may be encased in suitpreventing dirt or foreign matter from having access to said springs.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. In shock absorbing means for the boom of an excavating machine, in combination, a body, a boom comprising a foot member, pivot means for said -foot member disposed transverse to the longitudinalv axis of the boom and connecting the boom with the body of a machine, shock absorbing devices coacting with the foot member operable independently for absorbing twisting strains on the boom acting directly on either side member, and including parts movable simultaneously to absorb direct strains received -by both side members.

2. Means as claimed in claim 1, in which the last mentioned parts comprise cushion levers on said side members directly acting on the pivot means, and means yieldingly holding the cushion levers in said coaction with the pivot means.

3. In shock absorbing means for the boom of an excavating machine, in combination, a. boom comprising a foot member, pivot means for said foot member to connect the boom with the body of a machine, comprising separate shaft means transverse to the longitudinal axis of the boom, and separate yielding means on the foot member, each of said separate yielding means directly coacting with a respective one of the shaft means to independently resist but permit twisting movement of the boom on the shaft means.

4. In shock absorbing means for the -boom of an excavating machine, in combination, a boom comprising a `foot member, pivot means for said foot member to connect the boom with the body of a machine, comprising separate shaft means transverse to the longitudinal axis of the hoorn,V

and separate yielding means on the foot member, each of said separate yielding means directly coacting with a respective one of the shaft means to independently resist but permit twisting movement of the boom on the shaft means, and said yielding means being simultaneously operable to resist but permit bodily movement of the boom relative to both ends of the shaft means.

5. In combination, a shovel boom, means comprising a foot including spaced side members, separate pivot means for said side members to support the boom on a shovel machine body, and

individual cushion means on each side member independently and simultaneously yieldingly coacting directly with said pivot means.

6. The combination of claim 5, combined with bearing blocks movable on the side members and receiving the pivot means, said bearing blocks yieldably engaged by the cushion means'.

'1. The combination of claim 5, in which the cushion means comprises a lever fulcrumed on the adjacent side member, and means to hold the lever in yielding coaction with the boom pivot means.

8. In combination, a shovel boom, means comprising a foot including spaced side members, pivot means for said side members to support the Iboom on a shovel machine body, and mounting means yieldingly connecting the foot side -members to rock on said pivot means, asv a transverse axis, and including devices enabling each side member individually to rock laterally relatively to the pivot means and both side members to yield bodily or simultaneously.

9. In combination, a shovel boom, means comable housings or cylindrical casing members for prising a root including spaced side members,

pivot means for said side members to support the boom on a shove1 machine body, and mounting means yieldingly connecting the foot side members to rock on said pivot means, as a transverse axis, and including devices enabling each side member to rock laterally relatively to the pivot means under twisting stress on the boom, and both side members to move bodily relatively to the pivot means independently of axial movement on the pivot means, to absorb direct thrusting stress of the side members on the pivot means.

10. In combination, a shovel boom, means comprising a foot including spaced sidemembers, pivot means for said side members to support the boom on a shovel machine body, and a cushion means on each side member yieldingly coacting directly with said pivot means, the cushion means comprising a lever fulcrumed at one end on the adjacent side member, a bearing member for the pivot means movably carried by said side member and engaged by the intermediate portion of the. lever, and spring means yieldingly connected to the other end of the lever and engaging the side member to hold the lever in a predetermined position relative to the side member.

11. In combination, a shovel boom, means comprising a foot including spaced side members, pivot means for said side members to support the boom on a shovel machine body, and a cushion means on each side member yieldingly coacting directly with said pivot means, the cushion means comprising a lever fulcrumed at one end on the adjacent side member, a bearing member for the pivot means movably carried by said side member and engaged by the intermediate portion of the lever, and spring means yieldingly connected to the other end of the lever and engaging the side member to hold the lever in a predetermined position relative to the side member, the abutting portions of the lever and bearing member being spheroidal.

12. In a boom for cranes, or the like, in combination, a boom comprising a foot composed of spaced side members to pivotally support the boom, crane body support means for the foot including i'lxed pivot shafts, one shaft for each of said side members, and a yieldable member on each side foot member of the boom to connect such side member to its adjacent pivot shaft, and permitting yielding of either side member under torsional stresses applied to the boom, and yielding of both side members relative to their pivot shafts when simultaneous abnormal direct stresses are applied to the boom.

13. In a boom for cranes, or the like, in combination, a boom comprising a foot composed of spaced side members to pivotally support the boom, crane body support means for the foot including xed spaced supporting members, one for each side member of the foot, and yielding connecting devices pivotally attaching the side members of the foot to the supporting members each' pivot shaft, and yieldable means on theboom foot engaging each bearing member to resist movement of the bearing member under direct and torsional stresses applied to the boom. RAYMOND A. BECKWITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,670,470 Menck May 22, 1928 1,739,175 Mitchell et al Dec. 10, 1929 1,954,119 Derrah Apr. 10, 1934 2,066,600 Wilson Jan. 5, 1937 Re. 21,405 Stiehl Mar. 19, 1940 

